1. Field of the Invention
This invention relates to field access techniques for propagating magnetic bubble domains in a closely packed lattice in which the bubble domains interact with one another, and more particularly to the use of arrays of chevron shaped magnetic elements for propagation of bubble domains in a lattice.
2. Description of the Prior Art
Information systems using lattices of magnetic bubble domains are shown in copending U.S. patent applications Ser. No. 395,336, filed Sept. 7, 1973 now abandoned and Ser. No. 429,601, filed January 2, 1974. Additionally, B. A. Calhourn et al described the use of bubble lattices for information storage (Paper 7D-1) at the 20th Annual Conference on Magnetism and Magnetic Materials, held December 3-6, 1974, at San Francisco, California. At this conference, papers 7D-2 by L. L. Rosier et al, 7D-3 by J. S. Eggenberger, and 7D-4 by Ta-Lin Hsu also described different aspects of devices using magnetic bubble domain lattices. All of these papers were later published in the AIP Conference Proceedings No. 24 - Magnetism and Magnetic Materials-1974, pp. 617-626.
In these prior art bubble lattice devices, propagation of the lattice is generally achieved using conductor propagation. In these techniques, magnetic field gradients produced by currents in conductors move the lattice in order to access a portion of the lattice.
An alternative to the use of conductors for moving bubble lattices is described in aforementioned Ser. No. 429,601 and aforementioned paper 7D-2 (as well as in U.S. 3,930,244). In these references, translation of the lattice is achieved using buffer regions located at opposing ends of the lattice. The buffer regions contain parallel stripe domains which can be changed in size or number in order to shift the lattice back and forth. However, conductor patterns are still used to change the stripe domain patterns in the buffer zones.
Field accessing of magnetic bubble lattices is described in aforementiond Ser. No. 604,978. However, the patterns described there do not as closely conform to the lattice as the chevron patterns of the present invention and cannot be used to move the lattice along either its 0.degree. axes or its 60.degree. axes, which is possible using the asymmetric chevron patterns of the present invention. Further, the chevron arrays of the present invention enable multiple numbers of bubble domain rows and columns to be associated with each row and column of chevron elements. This means that less magnetic chevron elements are required while still providing reliable lattice translation.
Accordingly, it is a primary object of the present invention to provide an improved technique for translation of a magnetic bubble domain lattice using field access.
It is another object of the present invention to provide a technique for moving interacting magnetic bubble domains in a lattice using chevron shaped magnetic elements.
It is still another object of the present invention to provide a technique for translating multiple rows of bubble domains in a lattice by a single row of magnetic elements.
It is another object of the present invention to provide a technique for moving multiple columns of bubble domains in a bubble domain lattice by a single column of magnetic elements.